WDXS31 PGTW 090300 MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/PROGNOSTIC REASONING FOR TROPICAL CYCLONE 11S (FREDDY) WARNING NR 054// RMKS/ 1. FOR METEOROLOGISTS. 2. 6 HOUR SUMMARY AND ANALYSIS. SUMMARY: INITIAL POSITION: 20.3S 39.6E INITIAL INTENSITY: 60 KTS GEOGRAPHIC REFERENCE: 119 NM NORTH-NORTHWEST OF EUROPA ISLAND MOVEMENT PAST 6 HOURS: NORTHWESTWARD AT 07 KTS SIGNIFICANT WAVE HEIGHT: 25 FEET SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION: AFTER A BURST OF RAPID INTENSIFICATION YESTERDAY, TC 11S (FREDDY) HAS ONCE AGAIN RAPIDLY WEAKENED UNDER STUBBORN MID-LEVEL SHEAR AND DRY AIR INTRUSION. ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY DEPICTS CONVECTIVE CELLS FLARING UP AROUND THE CENTER, BUT AT PRESENT THE CONVECTION REMAINS DISORGANIZED. WATER VAPOR IMAGERY INDICATES THE UPPER-LEVEL OUTFLOW, WHILE RADIAL IN NATURE, REMAINS LIMITED IN AREAL EXTENT WITH NO DISCERNABLE OUTFLOW CHANNELS EITHER TO POLEWARD OR EQUATORWARD. THE CIRA ADVECTED LAYER PRECIPITABLE WATER PRODUCT SHOWS COPIOUS AMOUNTS OF DRY THROUGH THE MID AND UPPER-LEVELS OF THE ATMOSPHERE, WHICH IS WRAPPING UP THE WEST SIDE OF THE CIRCULATION AND INTO THE CENTER. FINALLY, HIGH-RESOLUTION MODEL DATA SUGGESTS A WEDGE OF MODERATE TO HIGH SOUTHERLY SHEAR IS PUNCHING IN FROM THE SOUTH. THE CONGLOMERATION OF THESE NEGATIVE PARAMETERS HAS LED TO THE WEAKENING TREND SEEN OVER THE PAST 24 HOURS. A LACK OF RECENT HIGH-RESOLUTION MICROWAVE IMAGERY MEANS THE INITIAL POSITION IS ASSESSED WITH LOW CONFIDENCE, USING AN EXTRAPOLATION OF A 082221Z ATMS 183GHZ MICROWAVE IMAGE. THE INITIAL INTENSITY HAS BEEN LOWERED TO JUST 60 KNOTS, WITH MEDIUM CONFIDENCE. EARLIER SAR DATA INDICATED WINDS UP TO 94 KNOTS HOWEVER THESE WERE DEPICTED WITHIN AN AREA OF CONVERGENT FLOW THAT WAS ASSESSED AS NOT REPRESENTATIVE OF THE OVERALL INTENSITY. AGENCY FIX CURRENT INTENSITY (CI) ESTIMATES ARE ALL T4.5, BUT FINAL-T NUMBERS ARE FALLING RAPIDLY AND RANGE FROM T3.5 TO T4.0 AND THE ADT, AIDT, SATCON AND OPEN-AIIR ESTIMATES ARE ALL BELOW 60 KNOTS. THE SYSTEM IS MOVING RATHER SLOWLY ALONG THE NORTHEASTERN SIDE OF A DEEP STR TO THE SOUTHWEST, BUT A NER POSITIONED TO THE NORTHEAST IS PROVIDING A BIT OF COUNTER-FLOW, KEEPING FORWARD SPEED LOW. INITIAL WIND RADII BASIS: SCATTEROMETER DATA, SAR DATA CURRENT STEERING MECHANISM: NORTHEASTERN PERIPHERY OF A DEEP-LAYER SUBTROPICAL RIDGE (STR) CENTERED OVER AFRICA. AGENCY DVORAK AND AUTOMATED FIXES: PGTW: T4.5 - 77 KTS KNES: T4.5 - 77 KTS DEMS: T4.5 - 77 KTS FMEE: T4.5 - 77 KTS CIMSS SATCON: 55 KTS AT 082222Z CIMSS ADT: 49 KTS AT 090000Z FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: MARGINALLY FAVORABLE VWS: 5-10 KTS SST: 27-28 CELSIUS OUTFLOW: WEAK RADIAL OTHER FACTORS: DRY AIR INTRUSION ANALYSIS CONFIDENCE: INITIAL POSITION: LOW INITIAL INTENSITY: MEDIUM INITIAL WIND RADII: MEDIUM 3. FORECAST REASONING. SIGNIFICANT FORECAST CHANGES: INTENSITIES ON EARLIER POSITIONS HAVE BEEN LOWERED SIGNIFICANTLY, THUS THE FORECAST INTENSITY HAS BEEN ADJUSTED 30 KNOTS LOWER. FORECAST DISCUSSION: TC FREDDY IS EXPECTED TO CONTINUE SLOWLY TRACKING NORTHWESTWARD ALONG THE NORTHEASTERN SIDE OF THE STEERING RIDGE THROUGH THE NEXT 48 HOURS. THE SYSTEM WILL MAINTAIN A TRACK SPEED OF ROUGHLY FIVE KNOTS THROUGH LANDFALL, AS THE NER TO THE NORTHEAST COMPETES FOR DOMINANCE IN THE STEERING FLOW. TC FREDDY IS EXPECTED TO MAKE LANDFALL ALONG THE COAST OF MOZAMBIQUE AROUND TAU 48 BEFORE MOVING SLOWLY INLAND AND DISSIPATING. IN THE NEAR-TERM, SOUTHERLY MID-LEVEL SHEAR AND CONTINUED DRY AIR INTRUSION WILL KEEP A LID ON INTENSIFICATION AND IT IS LIKELY TO EVEN WEAKEN A BIT MORE OVER THE FIRST 12 HOURS OF THE FORECAST. AFTER TAU 24 HOWEVER, CONDITIONS ARE EXPECTED TO IMPROVE, WITH THE ATMOSPHERE MOISTENING UP AND THE MID-LEVEL SHEAR DROPPING OFF TO MORE REASONABLE AND SUPPORTIVE LEVELS. AT THE SAME TIME THE SYSTEM WILL BEGIN MOVING OVER AN AREA OF ENHANCED OCEAN HEAT CONTENT (OHC) WHICH LIES JUST OFFSHORE OF MOZAMBIQUE. THE ONLY CAP ON INTENSIFICATION WILL BE THE RELATIVELY LIMITED OUTFLOW, WITH DEVELOPMENT OF A POLEWARD OR EQUATORWARD CHANNEL NOT EXPECTED. THE SYSTEM IS EXPECTED TO REACH PEAK INTENSITY OF 75 KNOTS IMMEDIATELY PRIOR TO LANDFALL. ONCE ASHORE, THE SYSTEM WILL RAPIDLY WEAKEN AND DISSIPATION BELOW WARNING CRITERIA IS EXPECTED BY TAU 96. MODEL DISCUSSION: WITH THE EXCEPTION OF THE GFS DETERMINISTIC TRACKER WHICH WILL BE DISCUSSED IN THE ALTERNATE SCENARIO BELOW, TRACK GUIDANCE IS IN GOOD AGREEMENT ON NORTHWESTWARD TRACK, THOUGH THERE ARE SIGNIFICANT ALONG-TRACK DIFFERENCES BETWEEN THE CONSENSUS MEMBERS. THE ALONG-TRACK SPREAD BEGINS TO EMERGE AS EARLY AS TAU 24, WITH THE EUROPEAN MODELS (ECMWF, ECENS, UKMET) FAR OUTRACING THE AMERICAN MODELS (GFS, GEFS, HWRF, NVGM), AND THIS TREND CONTINUES AND GROWS LARGER THROUGH THE FORECAST PERIOD. SO WHILE CONFIDENCE IN THE DIRECTION OF MOVEMENT IS HIGH, THE ENHANCED ALONG-TRACK SPREAD LEADS TO LOW CONFIDENCE IN THE OVERALL TRACK FORECAST. INTENSITY GUIDANCE IS MIXED, WITH ALL MODELS SHOWING A TREND LINE THAT BASICALLY CONFORMS WITH THE JTWC FORECAST, WITH THE NOTABLE EXCEPTION OF BOTH VERSIONS OF COAMPS-TC, WHICH SHOW SIGNIFICANTLY MORE INTENSIFICATION, TO A PEAK OF 100 KNOTS, BY TAU 48. THE JTWC FORECAST LIES ABOUT FIVE KNOTS ABOVE THE CONSENSUS MEAN THROUGH LANDFALL, THEN SLIGHTLY BELOW THE MEAN THEREAFTER WITH MEDIUM CONFIDENCE. AS MENTIONED ABOVE THE GFS AND TO A LESSER EXTENT THE GEFS ENSEMBLE, CONTINUE TO SHOW AN ALTERNATE TRACK SCENARIO FOR TC 11S, WHICH AFTER MAKING A RUN TOWARDS THE COAST, TOUCHING A TOE ON LAND AROUND TAU 72, THEN MAKES A U-TURN, AND MOVING BACK OUT TO SEA BY TAU 120. ANALYSIS OF THE UPPER-LEVEL STEERING PATTERN REVEALS THAT THE GFS BREAKS DOWN THE STR TO THE SOUTHWEST WHILE BUILDING THE NER TO THE NORTHEAST AS THE SYSTEM MAKES LANDFALL AND THUS THE STEERING PATTERN SHIFTS TO THE NER. THIS IS DIRECTLY OPPOSITE OF THE ECMWF SOLUTION. THE GFS HAS BEEN SHOWING VARIATIONS OF THIS THEME FOR SEVERAL RUNS AND THUS CANNOT BE FULLY DISCOUNTED EVEN THOUGH IT IS SO FAR, THE ONLY MODEL THAT SHOWS THIS SOLUTION. FORECAST CONFIDENCE: TRACK 0 - 72 HR: LOW TRACK 72-120 HR: LOW INTENSITY 0 - 72 HR: MEDIUM INTENSITY 72-120 HR: MEDIUM// NNNN